// SPDX-License-Identifier: GPL-2.0+
/*
 * Procedures for creating, accessing and interpreting the device tree.
 *
 * Paul Mackerras	August 1996.
 * Copyright (C) 1996-2005 Paul Mackerras.
 *
 *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
 *    {engebret|bergner}@us.ibm.com
 *
 *  Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net
 *
 *  Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell and
 *  Grant Likely.
 */

#define pr_fmt(fmt)	"OF: " fmt

#include <linux/bitmap.h>
#include <linux/console.h>
#include <linux/ctype.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_graph.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/proc_fs.h>

#include "of_private.h"

LIST_HEAD(aliases_lookup);

struct device_node *of_root;
EXPORT_SYMBOL(of_root);
struct device_node *of_chosen;
struct device_node *of_aliases;
struct device_node *of_stdout;
static const char *of_stdout_options;

struct kset *of_kset;

/*
 * Used to protect the of_aliases, to hold off addition of nodes to sysfs.
 * This mutex must be held whenever modifications are being made to the
 * device tree. The of_{attach,detach}_node() and
 * of_{add,remove,update}_property() helpers make sure this happens.
 */
DEFINE_MUTEX(of_mutex);

/* use when traversing tree through the child, sibling,
 * or parent members of struct device_node.
 */
DEFINE_RAW_SPINLOCK(devtree_lock);

bool of_node_name_eq(const struct device_node *np, const char *name)
{
	const char *node_name;
	size_t len;

	if (!np)
		return false;

	node_name = kbasename(np->full_name);
	len = strchrnul(node_name, '@') - node_name;

	return (strlen(name) == len) && (strncmp(node_name, name, len) == 0);
}
EXPORT_SYMBOL(of_node_name_eq);

static bool __of_node_is_type(const struct device_node *np, const char *type)
{
	const char *match = __of_get_property(np, "device_type", NULL);

	return np && match && type && !strcmp(match, type);
}

int of_n_addr_cells(struct device_node *np)
{
	u32 cells;

	do {
		if (np->parent)
			np = np->parent;
		if (!of_property_read_u32(np, "#address-cells", &cells))
			return cells;
	} while (np->parent);
	/* No #address-cells property for the root node */
	return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
}
EXPORT_SYMBOL(of_n_addr_cells);

int of_n_size_cells(struct device_node *np)
{
	u32 cells;

	do {
		if (np->parent)
			np = np->parent;
		if (!of_property_read_u32(np, "#size-cells", &cells))
			return cells;
	} while (np->parent);
	/* No #size-cells property for the root node */
	return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
}
EXPORT_SYMBOL(of_n_size_cells);

static struct property *__of_find_property(const struct device_node *np,
					   const char *name, int *lenp)
{
	struct property *pp;

	if (!np)
		return NULL;

	for (pp = np->properties; pp; pp = pp->next) {
		if (of_prop_cmp(pp->name, name) == 0) {
			if (lenp)
				*lenp = pp->length;
			break;
		}
	}

	return pp;
}

struct property *of_find_property(const struct device_node *np,
				  const char *name,
				  int *lenp)
{
	struct property *pp;
	unsigned long flags;

	raw_spin_lock_irqsave(&devtree_lock, flags);
	pp = __of_find_property(np, name, lenp);
	raw_spin_unlock_irqrestore(&devtree_lock, flags);

	return pp;
}
EXPORT_SYMBOL(of_find_property);

struct device_node *__of_find_all_nodes(struct device_node *prev)
{
	struct device_node *np;
	if (!prev) {
		np = of_root;
	} else if (prev->child) {
		np = prev->child;
	} else {
		/* Walk back up looking for a sibling, or the end of the structure */
		np = prev;
		while (np->parent && !np->sibling)
			np = np->parent;
		np = np->sibling; /* Might be null at the end of the tree */
	}
	return np;
}

/*
 * Find a property with a given name for a given node
 * and return the value.
 */
const void *__of_get_property(const struct device_node *np,
			      const char *name, int *lenp)
{
	struct property *pp = __of_find_property(np, name, lenp);

	return pp ? pp->value : NULL;
}

/*
 * Find a property with a given name for a given node
 * and return the value.
 */
const void *of_get_property(const struct device_node *np, const char *name,
			    int *lenp)
{
	struct property *pp = of_find_property(np, name, lenp);

	return pp ? pp->value : NULL;
}
EXPORT_SYMBOL(of_get_property);


/**
 * __of_device_is_compatible() - Check if the node matches given constraints
 * @device: pointer to node
 * @compat: required compatible string, NULL or "" for any match
 * @type: required device_type value, NULL or "" for any match
 * @name: required node name, NULL or "" for any match
 *
 * Checks if the given @compat, @type and @name strings match the
 * properties of the given @device. A constraints can be skipped by
 * passing NULL or an empty string as the constraint.
 *
 * Returns 0 for no match, and a positive integer on match. The return
 * value is a relative score with larger values indicating better
 * matches. The score is weighted for the most specific compatible value
 * to get the highest score. Matching type is next, followed by matching
 * name. Practically speaking, this results in the following priority
 * order for matches:
 *
 * 1. specific compatible && type && name
 * 2. specific compatible && type
 * 3. specific compatible && name
 * 4. specific compatible
 * 5. general compatible && type && name
 * 6. general compatible && type
 * 7. general compatible && name
 * 8. general compatible
 * 9. type && name
 * 10. type
 * 11. name
 */
static int __of_device_is_compatible(const struct device_node *device,
				     const char *compat, const char *type, const char *name)
{
	struct property *prop;
	const char *cp;
	int index = 0, score = 0;
	printk("__of_device_is_compatible finish\n");
BUG();
	return score;
}
/**
 *	of_get_parent - Get a node's parent if any
 *	@node:	Node to get parent
 *
 *	Returns a node pointer with refcount incremented, use
 *	of_node_put() on it when done.
 */
struct device_node *of_get_parent(const struct device_node *node)
{
	struct device_node *np;
	unsigned long flags;

	if (!node)
		return NULL;

	raw_spin_lock_irqsave(&devtree_lock, flags);
	np = of_node_get(node->parent);
	raw_spin_unlock_irqrestore(&devtree_lock, flags);
	return np;
}
EXPORT_SYMBOL(of_get_parent);

static struct device_node *__of_get_next_child(const struct device_node *node,
						struct device_node *prev)
{
	struct device_node *next;

	if (!node)
		return NULL;

	next = prev ? prev->sibling : node->child;
	for (; next; next = next->sibling)
		if (of_node_get(next))
			break;
	of_node_put(prev);
	return next;
}
#define __for_each_child_of_node(parent, child) \
	for (child = __of_get_next_child(parent, NULL); child != NULL; \
	     child = __of_get_next_child(parent, child))

/**
 *	of_get_next_cpu_node - Iterate on cpu nodes
 *	@prev:	previous child of the /cpus node, or NULL to get first
 *
 *	Returns a cpu node pointer with refcount incremented, use of_node_put()
 *	on it when done. Returns NULL when prev is the last child. Decrements
 *	the refcount of prev.
 */
struct device_node *of_get_next_cpu_node(struct device_node *prev)
{
	struct device_node *next = NULL;
	unsigned long flags;
	struct device_node *node;

	if (!prev)
		node = of_find_node_by_path("/cpus");

	raw_spin_lock_irqsave(&devtree_lock, flags);
	if (prev)
		next = prev->sibling;
	else if (node) {
		next = node->child;
		of_node_put(node);
	}
	for (; next; next = next->sibling) {
		if (!(of_node_name_eq(next, "cpu") ||
		      __of_node_is_type(next, "cpu")))
			continue;
		if (of_node_get(next))
			break;
	}
	of_node_put(prev);
	raw_spin_unlock_irqrestore(&devtree_lock, flags);
	return next;
}
EXPORT_SYMBOL(of_get_next_cpu_node);

struct device_node *__of_find_node_by_path(struct device_node *parent,
						const char *path)
{
	struct device_node *child;
	int len;

	len = strcspn(path, "/:");
	if (!len)
		return NULL;

	__for_each_child_of_node(parent, child) {
		const char *name = kbasename(child->full_name);
		if (strncmp(path, name, len) == 0 && (strlen(name) == len))
			return child;
	}
	return NULL;
}

struct device_node *__of_find_node_by_full_path(struct device_node *node,
						const char *path)
{
	const char *separator = strchr(path, ':');

	while (node && *path == '/') {
		struct device_node *tmp = node;

		path++; /* Increment past '/' delimiter */
		node = __of_find_node_by_path(node, path);
		of_node_put(tmp);
		path = strchrnul(path, '/');
		if (separator && separator < path)
			break;
	}
	return node;
}

/**
 *	of_find_node_opts_by_path - Find a node matching a full OF path
 *	@path: Either the full path to match, or if the path does not
 *	       start with '/', the name of a property of the /aliases
 *	       node (an alias).  In the case of an alias, the node
 *	       matching the alias' value will be returned.
 *	@opts: Address of a pointer into which to store the start of
 *	       an options string appended to the end of the path with
 *	       a ':' separator.
 *
 *	Valid paths:
 *		/foo/bar	Full path
 *		foo		Valid alias
 *		foo/bar		Valid alias + relative path
 *
 *	Returns a node pointer with refcount incremented, use
 *	of_node_put() on it when done.
 */
struct device_node *of_find_node_opts_by_path(const char *path, const char **opts)
{
	struct device_node *np = NULL;
	struct property *pp;
	unsigned long flags;
	const char *separator = strchr(path, ':');

	if (opts)
		*opts = separator ? separator + 1 : NULL;

	if (strcmp(path, "/") == 0)
		return of_node_get(of_root);

	/* The path could begin with an alias */
	if (*path != '/') {
		int len;
		const char *p = separator;

		if (!p)
			p = strchrnul(path, '/');
		len = p - path;

		/* of_aliases must not be NULL */
		if (!of_aliases)
			return NULL;

		for_each_property_of_node(of_aliases, pp) {
			if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
				np = of_find_node_by_path(pp->value);
				break;
			}
		}
		if (!np)
			return NULL;
		path = p;
	}

	/* Step down the tree matching path components */
	raw_spin_lock_irqsave(&devtree_lock, flags);
	if (!np)
		np = of_node_get(of_root);
	np = __of_find_node_by_full_path(np, path);
	raw_spin_unlock_irqrestore(&devtree_lock, flags);
	return np;
}
EXPORT_SYMBOL(of_find_node_opts_by_path);

/**
 *	of_find_node_by_type - Find a node by its "device_type" property
 *	@from:	The node to start searching from, or NULL to start searching
 *		the entire device tree. The node you pass will not be
 *		searched, only the next one will; typically, you pass
 *		what the previous call returned. of_node_put() will be
 *		called on from for you.
 *	@type:	The type string to match against
 *
 *	Returns a node pointer with refcount incremented, use
 *	of_node_put() on it when done.
 */
struct device_node *of_find_node_by_type(struct device_node *from,
	const char *type)
{
	struct device_node *np;
	unsigned long flags;

	raw_spin_lock_irqsave(&devtree_lock, flags);
	for_each_of_allnodes_from(from, np)
		if (__of_node_is_type(np, type) && of_node_get(np))
			break;
	of_node_put(from);
	raw_spin_unlock_irqrestore(&devtree_lock, flags);
	return np;
}
EXPORT_SYMBOL(of_find_node_by_type);

/**
 *	of_find_compatible_node - Find a node based on type and one of the
 *                                tokens in its "compatible" property
 *	@from:		The node to start searching from or NULL, the node
 *			you pass will not be searched, only the next one
 *			will; typically, you pass what the previous call
 *			returned. of_node_put() will be called on it
 *	@type:		The type string to match "device_type" or NULL to ignore
 *	@compatible:	The string to match to one of the tokens in the device
 *			"compatible" list.
 *
 *	Returns a node pointer with refcount incremented, use
 *	of_node_put() on it when done.
 */
struct device_node *of_find_compatible_node(struct device_node *from,
	const char *type, const char *compatible)
{
	struct device_node *np;
	unsigned long flags;

	raw_spin_lock_irqsave(&devtree_lock, flags);
	for_each_of_allnodes_from(from, np)
		if (__of_device_is_compatible(np, compatible, type, NULL) &&
		    of_node_get(np))
			break;
	of_node_put(from);
	raw_spin_unlock_irqrestore(&devtree_lock, flags);
	return np;
}
EXPORT_SYMBOL(of_find_compatible_node);
